perf(vncviewer): set nocasematch inside subshell

Author: akinomyoga

completions/vncviewer

@@ -83,13 +83,14 @@ _comp_cmd_xvnc4viewer()
             WMDecorationWidth ZlibLevel)
         [[ $cur == --* ]] && dash=-- || dash=-
 
-        local IFS=$' \t\n' reset=$(shopt -p nocasematch)
-        shopt -s nocasematch
-        local option
-        COMPREPLY=($(for option in "${options[@]}"; do
-            [[ $dash$option == "$cur"* ]] && printf '%s\n' "$dash$option"
-        done))
-        $reset
+        local IFS=$' \t\n'
+        COMPREPLY=($(
+            shopt -s nocasematch
+            local option
+            for option in "${options[@]}"; do
+                [[ $dash$option == "$cur"* ]] && printf '%s\n' "$dash$option"
+            done
+        ))
     else
         _comp_compgen_known_hosts -- "$cur"
     fi